Pulp refiner



PULP REFINER Filed Feb. 11, 1935 '7 Sheets-Sheet l K N g b In veni'or 0 N Max bikolflz'k M. SKOLNIK PULP REFINER Dec. 5, 1939.

Filed Feb. 11, 1935 7 Sheets-Sheet 2 M. SKOLNIK Dec. 5, 1939.

PULP REFINER Filed Feb. 11, 1935 7 Sheets-Sheet 3 Inventor f7 Ma; fijaolrz {It Dec. 5, 1939. M. SKOLNIK 2,182,391

PULP REFINER Filed Feb. 11, 1935 7 Sheets-Sheet 4 I n veni'or M. SKOLNIK PULP REFINER 7 Sheets-Sheet 5 Filed Feb. 11, 1935 bum,

IIIIIIIII/ 1939- M. SKOLNIK 2,182,391

PULP REFINER Filed Feb. 11, 1935 7 Sheets-Sheet 6 Inventor Max Skoznih:

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. 5, 1939. M. SKOLNIK PULP REFINER Filed Feb. 11. 1935 '7 Sheets-Sheet 7 EPatented Dec. 5, 1939 EE STATES PATENT OFFICE 2,182,391 PULP Barman Max' Skolnik, Chicago, 111.; assignor a. Natio 1 Fibre Corporation, New York, N. 3., a corpor tion of New York Application February 11.19;.5, sci-aim. 3,019

11 (on. sic-2o) This invention relates to the manufacture of pulp from fibrous organic material such as straw and the like, and particularly to processes and apparatus for treating such materials to produce pulp and certain by-products having commercial value.

My improved processes and apparatus are related to those disclosed in my Patents Nos. 1,865,-

649; 1,924,660; and 1,924,815; however, my present invention is directed particularly to unification and simplification of all the devices required to perform the several process steps, and tothe improvement of parts of the apparatus and of the entire process, whereby in one apparatus comprising several interrelated and coordinated mechanisms raw materials are, in a continuous and proin which the straw material treating liquors are self-fortified by chemicals extracted from the material being treated; to provide improved means for handling the material in bulk quantities during the chemical treatment thereof whereby the material is uniformly treated throughout its entire mass; to provide improved washing means for positively removingthe undesired constituents of the material after the same has been loosened by the chemical treatment; to provide such means that handle large quantities of material more rapidly than has been heretofore possible; to provide improved refining means; to provide refining apparatus that in one device performs the functions of several of the devices ordinarily used to obtain the same results; to provide such apparatus arranged in a relatively small simplified unit having several times the capacity of ordinary equipment; to provide such apparatus wherein the refining operation is performed continuously and in a single passage of the material through the mechanism.

Further objects are to provide an improved circuit and conditioning cycle for treatment liquors entrained with the treated materials whereby proper chemical conditions are maintained'; and to provide an improved device for effecting the refiner. r Fig. 7 is an elevation of the entering side of the first wheel of the refiner. 25

Fig. .8 is a similar view showing the entering side recovery of chemicals and the refining of valuable lignin by-products.

A specific embodiment of my invention is shown in the accompanying drawings, in which:-

Figures 1A and 1B show in a side elevation a 5,

complete plant or-system for the'manufacture of pulp from straw and the like, and 'for recovering certain valuable lay-products, Fig. 1A showing one-half of the apparatus and Fig. 13 showing the other half, the apparatus being divided trans- 10 versely at approximately its middle.

Fig. 2 is a sectional elevationthrough the basket loading-chamber as taken on'line 2-2 of Fig. 1A.

Fig. 3 is an enlarged partially sectioned eleva:

tion showing in detail the main spraying com- 15 partment and the entering end- 01 the cooking tank.

Fig. 4 is a partially sectioned side elevation of a 3-stage pulp washer.

Fig. 5 is a'sectional view of the same taken on Q line 5--'5 of E18. 4.

Fig, 6 is a sectional elevation *showing the of the second wheel oi. the refiner.

Fig. -9 is asimila'r view showing the entering side of the third to eighth wheels inclusive of the so refiner.

Fig. 10 is a view showing in elevation the-9th to 12th wheels inclusive of the refiner.

. Fig. 11 is'a yiew showing the. 13th or last wheel of the refiner.

Fig. 12 is a view showing in elevationthe dial- 35 izer or soda and lignin separating apparatus.

Fig. 13 isa plan view showing one of the plates of the dializer as it would appear in a sectional view taken on 'line.l3-l3 of Fig. 12.

Fig. 14 is a similar view of an alternate plate of 40 the'dializer.

Fig. 15 is a sectional view taken transversely through a plurality of the plates/shown in Figs. 13

and 14, as would appear in a section taken on line l5-l5 of Fig. 13.

Fig. 16.is a similar view as would appear in a section taken on line IS-l6 of Fig. 14.

In the ordinary processes of reducing raw mate- L rials to a finished and refined pulp, by removing the encrusting and intercellular materials, such as 50 the resinous, siliceous, glutinous and other matters, harsh and prolonged treatment methods are employed with the result that, if a pure cellulosefibre is obtained, the fibres constituting the refined pulp are greatly'weakened and reduced to] undesirably short lengths. Also the apparatus is also one ordinarily requiring considerable time for its completion.

The washings or solution containing the encrusting and intercellular.materials, or lignins,

and entrained caustic soda, are usually treated in:

However such apparatus is large and expensive and the various apparatus to recover the soda.

process is ordinarily oneof evaporation and com,-

bustion in which the lignins are destroyed or consumed, no attempt being made to save them. By the present invention the treatment of the raw material is reduced to one continuous process, 1 from the loading of the raw material into the apparatus to the production of finished and completely refined pulp delivered in sheets at the. delivery or leaving end -of the apparatus; the timerequired for the refined pulp' productionis 1 reduced to a fraction ofthe time ordinarily required; and the recovery of the soda is accomplished continuously in a relatively simple separating apparatus which also preserves the lignins for the production of valuable commercial by- 1 products.

1 es, so interrelated that there is one continuous As shown in the drawings the invention is emj bodied in an apparatus which is in itself a practically complete plant for the production of refined pulp from raw material and the recovery of soda and lignins. The apparatus comprises mechanisms for accomplishing each step in the process- 1 fiow of material from the raw material entering 1 end to the refined pulp delivery end and a con-- f tinuous process of by-product recovery.

Raw material such as straw' or the like is I loaded into fenestrate or perforated baskets or f containers, by pneumatic means, in a loading 1 housing I from which the loaded basket passes i to an enclosed spraying and-preheating tunnel 2 where the material is thoroughly sprayed and l soaked with the caustic soda treating solution.

From the spraying tunnel the baskets of ma- 1 terial are automatically passed into a long en- 1 closedtunnel-like cooking tank 3, which is filled with a caustic soda solution automatically maintained at a concentration of approximately 2% l the baskets I6 are suspended between them on and at a temperature of about 200 to 212 F.

x intercellular constituents of the raw material are 1 601 During the cooking process the encrusting and loosened.

The baskets are automatically moved through the cooking tank and require about fifty-five l minutes to pass from the entering to the leaving 1 end where they are removed from the tank and 65 i emptied .upon a conveying means which carries 1 l the material to a washer 5.

carried to a dump 4 in which their contents are As the straw passes through the washer the now a refined pulp is passed to a device -comaieasei prising a plurality of cylinders 71 which pick up the pulp and transfer it to a felt blanket on which a sheet of pulp is built up, squeezed of its I excess free moisture, and passed to a cutting and stacking or'folding mechanism. The product being sheets of treated and refined pulp ready for any desired use.

As shown in Fig. 1A the washer. 5 is connected with a tank 8 in whichthe squeezings, or washed out lignins, are collected. This tank is a clarifier in which the heavier or solid materials may set-' tle out of the liquid leaving most of the lignins in solution and suspension. This liquid will be herein termed the dark liquor.

The dark liquor, or liquid, is taken from the tank 8 at the upper part thereof by means of a pump which delivers the liquor to a soda recovery device 9, herein termed the dializer, in which. the soda is extracted from the dark liquor and from which the dark liquor, now comprising mostly lignins, is passed into lignin storage tanks for use in the manufacture of certain by products.

The extracted soda, which is carried in a liquid vehicleas will be hereafter explained, is transferred from the dializer 9 to a storage tank from which it is later removed and passed through a caustic recharging equipment and tank 50 to a second storagetank ll. From the tank l l, the recharged liquid is passed through a series of settling towers 42, in which a precipitate of calcium carbonate is removed, and then by way of a conduit iii to caustic solution storage tanks It which supply the make-up treatment solution for the cooking tank 3.

p In order to facilitate a complete understand-' ing of my invention the apparatus will be described in detail in the same order or sequence as the steps involved in the handling of the material being treated. The first step is the introduction of the raw material into the apparatus which is done in the loading chamber 8.

The loading chamber l comprises an open ended tunnel-like housing which surrounds a convenient section of a suspended track l5 extending between the dump 4 and the soakingand preheating housing 2. The passage through the loading chamber is arranged to receive bas kets or carriers l6 which are carried by the track l5 and have top openings; and at'approximately the center of the chamber a raised portion I! is provided in which are located the discharge nozzles I 8 of a pneumatic conveying device l9 arranged to handle the straw or other like raw material for loading the baskets IS. The tracks.

I5 comprise a pair of spaced parallel rails and flanged wheels 20 mounted on trunnions extending from the basket ends, as shown in Fig. 2., 1 The baskets or carriers are rectangular fenestrate devices constructed of perforated plates or heavy wire mesh andare provided with a movupwardly extending transverse channels 22 which are spaced across the width of thebasket and which extend into the basket for approximately one-third its height. These channels. are walled so that the bottom of the basket is closed and As shown the nozzles l8 are disposed so that,

aisasei when a basket 16 is placed beneath them with its cover 2i opened, they will uniformly distribute the raw material into the basket.

The purpose of the loading chamber is to prevent any loose straw or dust from escaping; and to further assure that dust and straw particles will be confined, a spray 23 is provided to dampen or soak the materialas it is being loaded. Also other sprays 2d are located directly beneath the position of the channels 22 and directed upwardly to further soak the raw material in the basket and assure that all of the material load is wet. The sprays 23 and 2d are connected by suitable piping 25 to a pump 26 which handles hot caustic solution drawn'from the cooking tank 3. As shown in Figs. 1A and 2 the loading chamber is constructed with an inwardly sloping'bottom which connects with a drain 2! by means of which exing prevents the entrapment of air in the voids within the mass of raw material and the formation of air pockets which would prevent the treatment liquor from reaching the inner portions of the mass when the baskets are immersed in and passing through the tank 3.

After the baskets it have been completely filled in the loading chamber they are passed. along the track 15, which is inclined toward the spraying and preheating chamber 2, and into this chamber where they are again sprayed with hot treatment liquor, from both the'top'and the bottom, and where the mass of the material is brought up to a temperature approaching that of the liquid in the cookingtank 3.

By this second spraying operation the raw straw is thoroughly soaked and because of the preheating, the cooking treatment liquors have full effect upon the entire mass the moment the baskets enter the tank 3.,

As shown in Figs. 13 and 3, the spraying and preheating chamber is a tunnel-like construction disposed above the cooking tank 3. The entering end is open and the inner or leaving end communicates directly with the cooking tank through the top thereof. The floor of the spraying and preheating chamber 2 extends from its entrance to approximately its middle and the remainder of'its length opens into the tank 3. A plurality of sprays 28 and 2e arranged to discharge water against the top and bottom of the baskets l6 respectively are disposed in the openbottomed portion of the chamber 2. These sprays are supplied with hot caustic solution by the conduit 89, which leads from the pump 2t and since the baskets l require approximately ten or twelve minutes to pass through the chamber 2, the material held by the baskets is thoroughly saturated with treatment solution and thoroughly preheated.

As the baskets reach the'inner end of the spraying and preheating chamber 2, they are delivered onto an elevator 39 which automatically lowers them into the cooking tank As shown in Fig. 3 an end bumper 32 is provided to keep the baskets it from overrunning the elevator 3! after they are delivered onto the same.

Also a hydraulic braking arrangement, not shown, is provided to hold the next successive basket on the. track is until the elevator 38 has rated bottom or the chamber 2'exactly beneath the sprays Z9 is provided with a screen 33 which serves to catch any loose pieces of straw, and yet allow any of the sprayed solution not absorbed by the straw in the gaskets to pass directly down-, ward into the cooking tank 3.

As the elevator at delivers a basket it into the cooking tank 3, the basketis engaged by an automatic ram 35 which pushes the basket ofi from the elevator 35 and onto a track 35 which extends substantially the length of the cooking tank 8.

The cooking'tank 3 is a long, enclosed tunnellike structure so constructed that it will contain and support a sufll cient quantity of caustic soda treatment solution to completely cover the baskets it as they pass through the tank. The caustic. soda solution within the tank 3 is maintained at a temperature of from 200 to 212 F., by means of steam coils at which are disposed along the bottom of the tank and extend for substantially its entire length, and it is within this tank that the raw material is given its main treatment for loosening the lignins or encrusting intercellular and glutinous materials, which it is desired to remove from the straw, in order to produce a pulp that is substantially pure cellulose.

As will be apparent from Fig. 3 the baskets will pass along the track it and through the pro-.- heating chamber 2 by gravity. However, after they have been loaded into the cooking tank 3 they must be pushed along the track 35, which is substantially horizontal. Such movement or shifting of the baskets along the track 35 is accomplished by the plunger or ram ed which pushes the baskets on of the elevatqi'j ttfl, each basket pushing ahead of it the next preceding basket, thus moving an entire train of baskets through the tank 3.

As the baskets reach the leaving end of the tank 3 they are pushed onto an elevator 37 which raises them out of the tank 3 and delivers them, through the action of a ram ea, onto the upper end of the track E5 on which they pass to the dump 3. The elevator 31 is indicated diagrammaticallyand in dotted outline in Fig. 1A and is of the same construction as the elevator 3! at the entering end of the cooking tank 3. The detailed construction of these elevators being substantially immaterial to this invention, no attempt will be made to further describe them, it being sumcient that they are suitable for the herein indi cated purpose.

The elevators 3i and 31 are automatically controlled by means not shown or indicated, and likewise the rams 3d and 38 are automatically controlled. The elevators 3i and 3'! are raised and lowered in unison and as a basket It is delivered into the elevator 39 and lowered into the tank 3 the elevator 23'? which at that instant will be empty, is likewise lowered into the leaving end of the tankii. When the elevator 3i reaches its bottom position where it is alined with the track 35, the rain as automatically acts to push the basket it ofi the elevator and onto the track 35, pushing the preceding baskets ahead of it. Thus when the tank 3 is filled with baskets, each time a new basket is delivered into the same, a

basket at the leaving end will be pushed onto dii the'lowered elevator Then both elevators 5i and 3'8 are automatically raised to their upper position and the ram 38 automatically acts to push the raised basket off the elevator 31 and onto the track 95. At the same time the brake in the preheating tank 2 simultaneously retire cycle of basket handling is completely automatic. As the baskets are pushed off of the elevator at by the ram 38, they pass along .the downwardly inclined track 65 to the dump 6 where they are automatically inverted by apparatus not herein shown in detail, and their contents empties onto a lateral conveyor merely indicated at 59; in Fig. 1A. The conveyor 59 moves themass of treated material emptied thereonto lat erallyrelative to the cooking tank 5 and empties such material onto a hopper 65 where the mate- -rial falls onto an automatic drag'arrangement M which permits the mass of material to be uniformly delivered to a ,drag conveyor 52 which delivers the material to the washer 5. The drag arrangement M, whilenot shown in detail, is constructed so that it will engage the material falling into the hopper 40 and prevent it from choking the drag conveyor 52.

After the material'is carried out of the hopper by drag conveyor 42 it is removed therefrom by a plurality of rotating kickers 53 which serve the further purpose of breaking up any chunks or small masses of the material.

It is to be noted at this point that while such an arrangement is not shown, a drain pan may be provided beneath the lateral conveyor 59 so that any free treatment solution carried by the mass of material emptied out of the baskets may be drained away and emptied into the cooking tank 3 or otherwise suitably disposed of. 'After the material is fed into the washer 5, it is automatically passed therethrough in a continuous-fiow, and through several washer stages, to'a hydrator 33 where the washed pulp is mixed with and diluted byfresh water, a thorough mixing action being assured by a rotating beater wheel 55, disposed transversely of the hydrator' M which is in the form of a large tank.

As indicated in Fig. 1A the last stage of the washer 5 is fed with substantially fresh or-clear water, which is supplied through a pipe 45 from a source that will be hereafter described, the pipe 66 havinga connection 51? withthe washer shell or housing.

The last stage of the washer 5 is provided with a drain connection 58, at its entering end, which leads to the intake side of a pump, not shown, the

discharge side of which leads to the connection 59 at the leaving end of the next preceding washer stage. This next stage of the washer 5 islikewise provided with a drain connection 55 leading to a pump 5! which delivers washings from this stage of the washer to the first stage thereof through a connection 52.

At the bottom of the "entering end of the first section of the washer 5 is a connection 53 which leads to the settling tank 8 in which the washings containing the lignins and other materials removed from the straw by the washer are. col-' lected so that solids and other heavy undissolved materials removed from the straw in the washing operation may settle out.

The remaining mixture of ditsolved and suspended lignins herein termed thedark liquor the washer may be increased.

greener k The first's'ection 5.l comprises a double tubular shell in which are mounted a pair of oppositely rotating screw conveyors 5.2' and 5.3, one having aleft-hand helix and the other a right-hand helix, so that while rotating in opposite directions they will each convey material in the same axial direction. The-screws 5.2 and 5.3 are disposed in the. housing- 5.! so that their helical bladeswill overlap each other as shown in Fig. 5.

Thus as material is fed into the enteringiend or mouth 5.4, it isengaged by the screws 52 and.5.3 and carried by them through the'first washer stage to a connection 5.5 which leads to the mouth 5.5 of the second washer stage 5.1.

The parallel screws in the housing 5.l "are inter meshed with. each: other so that as the material is being conveyed axially through the housing it is squeezed between the intermeshed screw blades. The inner'walls of the housing 5.l, which are spaced away'fromtheedges of the screw blades are provided with axially extending. ribs 5.8 which project inwardly and substantially engage the edges of. the helical screw blades These ribs 5.8 serve to agitate or stir up the material passing through the washers and assist in the squeezing process.

The second and third stages 5.l and 5.9 respectively of the washer are constructed insubstantially the same manner asthe first stage 5.8 with the exception that the pitch of the conyeyor screws may be lessened in order that the squeezing action on the material passing through As shown in 'Fig. 4 the screws ofall of the washer stages may be rotated by a single driving not shown. vln such an arrangement the driv- Y to means 5.) which rece1ves its powerfrom a motor,

ing means 5.lil'm'ay be connected directly to the shafts 5H of the third washer stage screws, and

the power may be transferred by belts or the like M2 to the shafts 543 of the second washer stage screws. Likewise' the shafts 5J4 of the first stage washer screws may be driven by a belt 5J5 from; the shafts 5J3.

As shown in Fig. 4, fresh water is fed into the washer by means of the conduit and connection 67 which water in passing through the washer in a direction counter'to the movement of the material within the same serves as a vehicle as well as a rinsing agent, and in passing backwardly from stage to stage, through the agency of the pipe connections 48, 69, 5Il'and 52 and the associated pumps, one of which is shown at 55, carries with it the squeezed-out lignins in increasing concentration 'for final delivery of such lignins through the pipe 53 to the settling tank '8. After passing through. the third stage 5.9 of the washer, the material is discharged through the connection 5.-i6 into the hydrator 44.

After being diluted in the hydrator 44 the washed'pulp is conveyed through'a conduit 54 to a paddle-wheel beater 55 which feeds the material into the refiner 6, wherein the fibres are beaten and separated from each other and finally delivered as completely. refined pulp to a conduit 55having connection with the outlet end 57 of the refiner.

The paddle-wheel beater 55 is thenature of for thesame with the entering end of the refiner 6.

The central portion of the beater 55 has horizontally cylindrical side walls between which is mounted a paddle-wheel 58 which is rotated by a motor 59 through a belt 66 and which drags the pulp over a plurality of projections 6| on the inner surface of the beater walls. At the bottom of the beater 55 is a trap 62 provided with a clean-out door 63 for the removal of any heavy solid impurities that may have passed through the hydrator. I

The refiner 6 is shown in detail in Fig. 6 of the drawings, and comprises a plurality of cyilndrical sections arranged in an end to end series,

with each section having a greater diameter than the next preceding section.

The first section 6.1 is a pump and houses an impeller 6.2 which is shown in detail in Fig. 7,

which illustrates the same from the entering side. The walls of the section 6.! are provided with a plurality of axial ribs 6.3 which serve to effect a beating action on the pulp material as it passes through the pump impeller 6.2, and into the second stage 6.4 of the refiner.

The second refiner stage 6.4 houses a single wheel 6.5, the enteringside of which is shown in Fig. 8. The wheel 6.5 is made up of two identical sections arranged back to back, each comprising a disk on one face of which are formed a plurality of radially curved blades 6.6.

Thus, when the wheel 6.5 is rotated the leading surface of the blade 6.6 on the entering side will be convex and the leading surface of the blade 6.! on the leaving side willbe concave, whereby a centrifugally outward force will be applied to the material on entering the section 6.4 and a scooping inwar'd force will be applied to the material on the opposite side'of the wheel to expel the same from the section 6.4 axially into the next section 6.8, the entering. side of the wheel 6.5 acting as a centrifugal impeller and the leaving side acting as a pump to draw the material through the section.

The third stage 6.6 of the refiner as shown is divided intothree similar portions, each of which houses a wheel 6.9, the form of which is illustrated in Fig. 9.

The wheels 6.9 are similar to the wheels 6.5,

except that the blades are greater in number and are'not as wide, and this wheel is likewise made up of two identical sections like that shown in Fig. 9 arranged back to back so that the action of each wheel will be the same as that of the wheel 6.5.

The fourth stage 610 of the refiner is substantially the same as section 6.8 except that it is of greater diameter; and the wheels 6. housed therein are likewise of the same construction as the wheels 6.9 except that they are of greater diameter, and of lesser width.

The fifth stage 6.l2 of the refiner comprises four similar sections, each of which houses a wheel 6.l3 which is shown in Fig. 10. The wheel 6.l3 is provided on each face with a plurality of radial and annular ribs or blades and the periphery of this wheel is provided with a large number of closely spaced radially projecting blades. Both sides of the wheel 6. l3 are identical and this wheel may therefore be readily made in one single piece. I

The last or final stage. 6.! 4 of the'refiner is of the same diameter as the fifth stage 612, and comprises a single section housing, a pump wheel 615 which serves to expel the refined pulp into washer.

the outlet 5'7, the wheel 6.i5 being simply a paddle-wheel type impeller as shown in Fig. 11.

Each section of each stage of the refiner is provided with a plurality of annularly spaced ribs 6.l6 which extend radially along each section end wall and axially along the side wall whereby the pulp as it passes through the several refiner wheels is thoroughly beaten between the ribs 6.l6 and the blades of the wheel to separate the pulp fibres.

The clearance between the edges of the ribs. 6.l6 and the edges of the blades on the several wheels is of varying amounts, being widest in the first or intake and pumping section and decreasing slightly in each successive section, and in each portion of each section, progressively toward the last or discharge pump section. Thus as the pulp passes through the device it is subjected to a continuous and rapid centrifugal or turbinate whirling action between beating sections ofprogressively increasing fineness with the result that each other and the pulp substantially fiufled, the

fibres'being fine but long and possessing greater strength than is had in ordinary processes.

During the refining process it is necessary to mix fresh water with the pulp to further dilute it and aid in the separation of the fibres. water is supplied by a connection 64 which is a branch of the conduit 46 shown in Fig. 1A. The connection 64 is brought into a header 6." formed on the outside of the fifth stage 612 of the refiner, there being a plurality of small open-. ings 6.l6 in the side wall of each section of the stage 6." communicating with the interior of the header 6., whereby fresh water supplied by the connection 64 is distributed substantially uniformly to each section of the final refiner stage in relatively fine streams.

All of the refiner wheels are mounted on and carried by a single shaft 65 which extendsaxially through the refiner, and which is driven by a motor 66.

From the conduit 56 the refined pulp is delivered into a tank 61 in which a plurality of pulpcollecting cylinders l are mounted on horizontal axes. The pulp-collecting cylinders, while not shown in detail, are hollow cylindrical devices the 4 Such This sheet after passing As indicatedin Fig. 1B the couch rolls 1 are mounted on hollow trunnions which communicate with the interior of the rolls and a pipe II is connected between each hollow trunnion and a header 12 which is connected to the intake side of a pump I3, the discharge side of the pump being connected directly with the pipe 4'6which supplies fresh water to the refiner and to the The' water withdrawn from the tank 61 by the pipes 1| creates a flow of pulp-toward the cylindrical surface of each 'of the cylinders I so that as the water'passes through the wire mesh thereof the pulp is deposited on the outside of the mesh to be carried thereby upwardly to the felt blanket 68. Water removed from the tank 61 by the pump 13 and supplied to the refiner and washer is substantially replaced by the water which carpart of the purpose of the herein described invention to recover the caustic soda from the washings for use in making up fresh caustic soda solution for the cooking tank 3, the procedure being part of a continuous cycle of operation whereby make up soda is automatically provided to maintain the supply of treatment liquor at a proper concentration. As shown in Fig. 1A the washings held in the settling tank 8 are removed at the upper part of the tank by a pump it having intake connection with the tank 8 and a discharge connection 16 which leads to the soda recovery apparatus 9, the washings or dark liquor first passing through a heating tank 17 in which is mounted a steam coil I8 for the purpose of heating the dark liquor to a temperature suitable for the soda recovery process, the dark liquor being extracted from the tank 11 by a pump 19 and delivered by a conduit 80 to the soda recovery apparatus.

It has been found desirable in many cases to evaporate the dark liquor during the heating process in order to increase the concentration of the lignins in the liquor as it is delivered to the recovery device 9, thus obtaining a lignin by product containing a lesser amount of water, and it will be understood that the tank 17 may also be constructed to serve as an evaporator as well as a heater.

The soda recovery process is one utilizing the phenomena of dialysis which is a well known method of separating bodies based on their unequal difl'usibility characteristics, that is with a mixture of bodies having unequal diffusibility characteristics placed on one side of a porous membrane such as a sheet of parchment paper and placing water on the other side of the membrane, the body having the greatest diilusibility characteristic will pass through the membrane and into the water. Y i

In the soda recovery apparatus 9 the dark so-. lution is passed over one side of a porous membrane and substantially clear water is passed over the other side of the said membrane, the

soda, having the greatest diflusibility characteristic, passing through the membrane and into the water in which it is readily utilized as will be hereafter described. The substantially fresh water supply of the soda recovery apparatus is provided by a conduit 8| which is a branch of the conduit 46 asshown in Fig. 1B, the water being supplied by the pump 13 which takes such water from the tank 61. -I'he soda recovery apparatus of the dializer is shown in detail in-Figs. 12 to 16 inclusive.

zontal cross bars 9.4.

There are two supporting frames such as shown dializer sections 9.2 are supported between these As shown in Fig. 12 the dializer comprises a housing; 9.l in which a plurality of dializer sections 9.2 are supported on a steel frame-work comprising vertical steel members 9.3 and a plurality of horiaieasei frames on the cross-bars 9.6. Each dializer section is made up of a plurality of plates 9.5 and 9.6, such as shown in Figs. 13 and 14, arranged face to face alternately.

. A diaphragm of porous membrane M such as parchment or the like is disposed between each of the plates comprising the dializer section and these plates, together with the membrane 9.? are clamped together face to face as shown in Figs. 15 and 16 by a header plate 9.8 which is put under pressure by a screw jack 9.9. The liquids passing through the dializer plates travel in opposite directions relative to each other through passages in the plates as will be hereafter described. As shown in Fig. 12 the dark liquor taken from the tank ll by thepump vl9 enters the dializer atthe upper corner of one end and leaves at the diagonally opposite lower corner of the opposite end. It is preferable that the dark liquor from the tank Tl pass through the dializer sections serially and thus flexible connections 9.89 are connected between the dark liquor exit port of one section and the dark liquor entrance port of the next succeeding section, and after leaving the last or final dializer section the dark liquor passes through a conduit 9. to a lignin storage tank 82, the dark liquor entering the tank 92 having had substantially all of its soda content removed in the dializer.

As shown in Fig. 12, the conduit 9.96 is connected to the last dializer section by a flexible connection 9.12 in order to permit movement of the header plate 9.8 for the disassembly of the plates comprising the dializer sections.

The substantially,fresh water, herein termed H the white liquor, is supplied to the dializer sections through the pipe 8! which has connections I with the dializer sections on the same side thereof as the dark liquor exit ports, but at the corner vertically opposite the said dark liquor exit ports.

Thus the white liquor passes through the dializer in a direction opposite to that taken by the dark liquor and leaves the dializer at the corner vertically opposite the dark liquor entrance port.

As shown in Fig. 12 the white liquor passes through one section only of the several dializers, and the supply pipe 8| is connected with the several dializer sections by means of flexible branch connections 9J3, the white liquor exit connections 9. being connected to a header 915 which leads to a conduit 89.

In order to keep the liquors from cooling as they pass through the dializer and to maintain the temperature thereof at the point most suitable for maximum dializing action, a heating coil 9J6 is provided insome suitable portion of the housing 9.l such as at the bottom thereof as shown in Fig. 12.

Referring to Figs. 13 to 16 inclusive, it will be seen that the alternating dializer plates areeach provided with atortuous passageway which travels back and forth across the face of the plate from one corner thereof to a diagonally opposite corner thereof. The passageways of the two plates 9.5 and 9.6 are arranged so' as to be 'substantially in registration when the plates are set face to face. However the passageway of one plate begins and ends at horizontally opposite corners from which the passageway of the alternate plate begins and ends.

Referring indetail to Fig. 13 the passageway 9J1 of the plate 9.5 which shall be considered as a dark liquor plate begins at the upper left-hand corner of the plate as shown in Fig. 13 and travelsback and, forth across the face'of the plate terto span the passageway 9.01 in a manner shown in Fig. 13, the bridges being provided by leaving a portion of the material having about one-half the thickness of the plate at the time the plate is formed, the lesser thickness of the bridge 91d 1 permitting the liquor to pass by the same as it travels along the passageway Mil.

The plate 9.6 shown in Fig. 14 is substantially the same as the plate 9.5, except that the passageway 9.2! begins and ends at horizontally opposite corners of the plate, relative to the passageway of the plate 9.5, the passageway ELM bee ginning at the aperture 9.22, and ending at the aperture 9.23. v

. As heretofore stated, the passageways M? and 9.2i in the plates 9.5 and 9.6 respectively are arranged so as to be in registry when the plates are mounted face to face on the supporting bars 9t, and as will be noted from Figs. 15 and 16 the apertures 918 and 919 of the plate 9.5 will be in registry with apertures 92d and 9.25 of the plate 9.6, the latter two apertures having no connection with the passageway 9.2i. Likewise the apertures s22 and 9.23 of plate 6 will be in registry with apertures Q26 and 9.2? of plate 9.5 which likewise have-no connection with the passageway 917. Thus by referring to Figures 15 and 16, it will be seen that the registering apertures 9.i8 and 9.2%, of the alternate plates, form a continuous intake passageway through the assembled plates comprising the dializer section and likewise the registering apertures M9 and 9.25 form a continuous discharge passageway through the section, so that entering dark liquor flowing through the passageway formed by the registered apertures 9.58, and tit will flow through the channels an of the respective dark liquor plates 9.5 only, the membrane 9.! serving as a gasket between the adjacent plates 9.5 and 9.3.

Likewise with reference to Fig. 16 entering fresh water flowing through the passageway formed by the registering aperturesaflt and 9.26 will flow only through the channels 9.2l of the respective white liquor plates 9.6 to the exit passageway through the section formed by the regisare in registry-a. relatively large area of porous membrane is exposed to the two liquids. The white liquid is passed through one dializer section only, in order that a maximum absorption in each section may be had, and the dark liquor is passed through the several dializer sections serially in order to increase the length of its time in contact with the membrane to assure a maximum extraction of the soda from the dark liquor solution.

Upon leaving the soda recovery unit 9, the white liquor containing the extracted soda is carried by the pipe 83 to a'reclaimed soda storage tank 8 indicated in dotted outline in Fig. 1B. 1

From the storage tank 84 the white liquor is carried by a pipe 85 to a pump 86 and thence to a conduit 87 which branches through a twoway valve 88 to a connection 89 leading into a caustic solution-mixing equipment 90, the connection 89 being in the form of a spray pipe arranged to spray the liquor over a plurality of baskets ti which are filled with a mixture of lime and soda ash and which are arranged to be' turned or spun, in a manner and by a means not shown, in order to thoroughly saturate the solution sprayed by the pipe 89. The caustic solutionmixing equipment 90 is positioned directly over the tank It and is separated therefrom by a floor '92 in which are a series of dump valves 93 whereby the recharged liquid from the tank 90 can be released into the tank Iii.

A connection between the tank iii and conduit '35 is had through a three-way valve 94 which is employed in conjunction with the valve 88 to pro-. vide for recirculation of the liquid in the tank It through the'charging equipment 96 or for transferring the charged liquid from the tank ill to the elevated tank ii. From the tank ii the solution is slowly released into the series of settling towers E2 in which a precipitate of calcium carbonate is settled out of the liquid, the remaining caustic soda solution passing by means of the conduit is to the main storage tanks it.

The storage tanks it are arranged in series and the treatment solution is transferred from them to the cooking tank 3 by means of a pump and the intake and discharge pipes 95 and 9? respectively.

During the performance of the hereindescribed treatment process considerable soda normally present in the natural straw is removed therefrom during the cooking treatment, some of which is carried into the washer from which it passes into the settling tank 8. The soda which is released and dissolved in the cooking tank solution serves tracted from the straw that passes to the tank 8 is recovered in the dializer ii.

Normally several cooks or cooking tank loads of raw material are required before a chemical equilibrium in the treatment solution cycle is reached during which 'soda must be put into the system. However, after these several cooks, it is found that an excess of soda appears which must be removed from the system in order to keep the proper degree of concentration in the treatment solution and such excess soda upon removal 'tially refined and utilized as a by-product. The

by-product production finally reaching a'point where its value is greater than that of the pulp that is produced. Thus the entire apparatus may ultimately serve principally for the extraction of chemicals and lignins from straw andthe like and the pulp production may become or by-product factor.

a secondary from the spirit of this invention as defined Although but one specific embodiment of this invention has been herein shown and described, it will be understood that details of the disclosure may be modified or omitted without departing in the following claims.

I claim:

l. A pulp refining device comprising a shell having intake anddischarge openings, a rotatable shaft extending axially in said shell, a disc-like wheel mounted on said shaft and within said shell, a plurality of radially curved blades on the surface on each side of said disc-like wheel, the blades on one side of said wheel being curved away from the direction of rotation thereof and the blades on the other side being curved toward the said direction of rotation, and a plurality of spaced fins on the inner surface of. said shell pro-' jecting toward said wheel and extending in a direction transverse to the plane of rotation thereof.

2. A pulp beating wheel comprising a disc hav- 1 ing a central hub, and a plurality of radially curved blades projecting from the surface of each ,side of said disc, said blades extending radially the axis of said disc member and extending radi-,

ally beyond the periphery of said member where they are joined to form substantially radial pe ripheral fins.

4. A pulp beating wheel comprising a disc-like member having a central hub and a serrated periphery, and a plurality of blades projecting from the surface of each side of said disc member, said blades extending radially outward toward the periphery of said disc member and each terminating at the crest of a respective one of said serrations. 5. A pulp beating wheel comprising a disc-like member having aicentral hub and a serrated periphery, anda plurality of radially curved blades projecting from the surface of each side of said disc member, said blades extending radially outward toward the periphery of said disc member,

each-terminating at the crest of a respective one of said serrations, and the blades on the two sides of said disc being curved in respectively opposite angular directions. e

6. A pulp refining device comprising a plurality of cylindrical'stages of progressively increasing its axis, and each of said sections having a plurality of fins on its inner surface, saidfins projecting toward the respective wheel and extending ina direction transverse to the plane of rotation thereof.

7. A pulp beating wheel comprising a disc-like member-having a central hub, and a plurality of blades on the surface of each side of said disc-like member, said blades being spaced angularly about the axis of said disc-like member and extending radially beyondthe periphery of said member peripheral fins, and the blades on the two sides of said disc being curved in respectively opposite angular directions.

8. A pulp refining device comprising a shell defining a pulp beating chamber having a substantially cylindrical outer wall and spaced, substantially parallel, end walls, intake and discharge openings in the end walls, a rotatable shaft extending through the openings, a beater wheel secured on the shaft for rotation within the chamber and having an outer. periphery extending radiallybeyond the openings, a plurality of circumferentially spaced fins on the inner surface of the shell and directed substantially radially toward the wheel, said fins being substantially U- shaped and extending substantially continuously across both end walls and the outer wall of the chamber between the inlet and outlet openings, adjacent fins forming a series of circumferentially arranged U-shaped pockets enveloping peripheral marginal portions of the wheel, and a plurality of ribs on the wheel arranged for cooperative beating action with the fins on the shell upon rotation of the wheelto separate the fibres of material carried through the shell in suspension.

9. A pulp refining device comprising a shell de- 0 fining-a pulpibeating chamber having a substan-- tially cylindrical outer wall and spaced, substantially parallel, end walls, intake and discharge openings in the end walls, a rotatable shaft ex-' tending through the openings, a beater wheel se-v marginal portions of the wheel, and a plurality of ribs on the wheel arranged for cooperative beating action with the fins on the-shell upon rotation of the wheel, said wheel ribs being substantially radially disposed and extending. beyond the peripheral margins of the wheel to permit the passage of material between adjacent ribs from one side of the wheel to the other in" the beater cham-,

ber.

10. A pulp refining device comprising a shell defining a pulp beating chamber having a substantially cylindrical outer wall and spaced, substantially parallel, end walls, intake and discharge openings in the end walls, a rotatable shaft extending through the ope ings, a beater wheel secured on the shaft for rotation within the chamber and having an outer periphery extending radially beyondthe openings, a plurality of circumferentially spaced fins on the inner surface of the shell and directed substantially radially toward the wheel, said fins being substantially U-shaped and extending substantially continuously across both end walls and the outer wall of the chamber between the inlet and outlet openings, adjacent fins forming a series of circumferentially arranged U-shaped pockets enveloping peripheral sides of the beater wheel, the ribs on one side where they are joined toform substantially radial cooperating with fins on the end wall of the 2,182,891 chamber having the inlet opening and the ribs on the opposite side of the wheel cooperating with the fins on the end wall of the chamber having the outlet opening. 7

11. A'pulp refining device comprising a shell dea pulp beating chamber having a substantially cylindrical outer wall and spaced, substantially parallel, end walls, intake and discharge openings in the end walls, a rotatable shaft extending through the openings, a beater wheel secured on the shaft jor rotation within the chambe!" and having an outer periphery extending radially beyond the openings, a plurality of circumferentially spaced fins on the inner surface of the shell and directed substantially radially toward the wheel, said fins being substantially U- shaped and extending substantially continuously 1 across both end walls and the outer wall or the 1 inlet opening side chamber between the inlet and outlet openings, adjacent fins forming a series of circumferentially arranged U-shaped. pockets enveloping peripheral marginal portions of the wheel, and a plurality of ribs on both sides of thebeater wheel arranged for cooperative beating action with the fins on the shell upon rotation of the fibres of material carried through the shell in the wheel to separate suspension, said ribs substantially radially disposed with respect to the shaft and extending beyond the peripheral margins of the wheel so that suspended material passes between adjacent ribs in moving through the chamber around the wheel periphery from the thereof to the outlet opening side thereof.

U-shaped pockets of the 

